A micro/nano structure having a size of several nm to several hundred nm is manipulated and controlled in nano scale. Thus, new physical/chemical properties different from those of existing materials can be expected. Therefore, the micro/nano structure has been attracting a lot of attention as a next-generation material which can overcome the limitations of the existing materials.
Such a micro/nano structure is one type of core new material that provides a foundation for use in technologies of various fields such as organic light emitting elements, liquid crystal displays, touch panels, or solar cells. Generally, a micro/nano structure is manufactured to various sizes by a chemical method, and micro/nano structures are coated on a substrate by bar coating, spray coating, spin coating, dip coating, brush coating, gravure coating, or the like. Various techniques for manufacturing a substrate including micro/nano structures with excellent properties have been developed.
For example, Korean Patent Laid-open Publication No. 10-2013-0037483 (Application No. 10-2011-0101907) discloses a method for manufacturing a conductive film by forming a one-dimensional conductive nanomaterial including any one selected from a carbon nanotube, a metal nano wire, and a metal nano rod and forming a two-dimensional nanomaterial including any one selected from graphene, boronitride, and tungsten oxide on an upper surface of the one-dimensional conductive nanomaterial.
Meanwhile, if micro/nano structures having different sizes are used in a transparent electrode or the like, conductivity and transmittance are decreased and haze is increased. Accordingly, various techniques for manufacturing uniform-sized micro nano structures have been developed.
For example, Korean Patent Laid-open Publication No. 10-2013-0072956 (Application No. 10-2011-0140589) discloses a method for forming a metal nano wire by allowing a reaction solution to pass through a filter having a pore size of 5 μm to 10 μm.
Further, various techniques for reducing a resistance of a micro/nano structure network have been developed. Particularly, as for a silver nano wire, there has been suggested a method of performing a heat treatment, an acid steam treatment, and a graphene oxide treatment after coating. However, such methods have a problem of damaging micro/nano structures or a substrate on which the micro/nano structure are disposed.